Identification of pod borer resistant pigeonpea: an introgression breeding with Cajanus scarabaeoides accompanied by integrated screening

Abstract

Pod borer, Helicoverpa armigera Hubner is a major insect pest inflicting significant losses in pigeonpea, Cajanus cajan (L.). Lack of viable pod borer resistant source in the primary gene pool of pigeonpea has led to initiation of pre-breeding programmes with wild Cajanus species. The present study was conducted with 38 promising introgressed lines (ILs) derived from Cajanus scarabaeoides (L.) Thouars into agronomic background of ‘early 3’ and ‘UPAS120’. The ILs were screened for pod borer resistance under natural field infestation during kharif 2019–2021 along with the reference genotypes. The pod fly, Melanagromyza obtusa Malloch (14.39–29.11%) and pod borer (1.78–2.52%) has recorded highest mean percent pod damage. The 2 IL’s, WDBCE 6-3-4-6 and WDBCE 6-3-4-7 were found to be pod borer resistant based on PRSR score (4, 4 and 3) and the same has been confirmed in detached pod, no-choice assay. The lower infestation was correlated to the higher phenol content (14.21 and 11.52) and lower total soluble sugar (TSS) (29.96 and 27.34) in the resistant genotypes. Further, PCA-biplot analysis on seven morphometric traits revealed that 4 morphological traits (pod wall thickness, pedicel length, seed thickness, and seed length) and 2 floral characters viz., ‘purple’ colored flowers with ‘sparse’ streak pattern were strongly associated with WDBCE 6-3-4-6 and WDBCE 6-3-4-7. The identified 2 genotypes hold immense potential as pod borer resistance donor in further breeding program or it may be released as varieties after confirming the yield stability in the multilocation trials.